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What is the genome and what does it do? - OCR 21st CenturyThe genome

Humans and other organisms look a lot like their parents. This is because they have inherited information from them. This information is stored in the genome of the organism.

Part of Biology (Single Science)You and your genes

The genome

The is the entire genetic material of an organism. It is found in the nucleus of a cell, and is composed of a chemical called . The study of the structure and function of the genome is called .

DNA is a - a large and complex molecule. The that make it are called . DNA is made up of two strands forming a twisted ladder structure called a . The nucleotides are arranged along the DNA to form a code. This determines the characteristics of a living .

Genomes of different organisms

Genetic material for is in their . such as bacteria do not have nuclei. Their genetic material is in the cytoplasm and includes small loops of DNA called .

Genes and chromosomes

Many nucleotides form each gene. A gene is a small section of genetic code in the DNA of a chromosome. Each gene codes for a particular sequence of in order to make a specific protein. It is a unit of , and may be copied and passed on to the next generation.

This diagram shows the relationship between the cell, its nucleus, chromosomes in the nucleus, and genes.

Diagram showing a chromosome and its DNA

Scientists now know that genes only make up a small part of an organism's DNA. Most DNA - 98.5 per cent in humans - does not code for proteins. Instead, it seems to be important in controlling . This means it controls when genes are 'read' to make proteins.

The genes and non-coding DNA are mixed together in the . These are long threads of DNA, which carry the genetic code. An organism's genetic code is made up of many genes.